1. Field of the Invention
The present invention relates to a machine tool provided with an automatic tool changing apparatus.
2. Description of the Prior Art
There is a known machine tool provided with an automatic tool changing apparatus, in which a tool magazine is mounted on a table which is movable along two axes perpendicular to each other, in a plane perpendicular to an axis of a spindle of the machine. With this known machine transfer of tools between the tool magazine and the spindle is performed by movement of the table along the axis perpendicular to the axis of the spindle and relative movement between the tool magazine and the spindle along the axis of the spindle. However, this machine tool has a disadvantage in that the area on the table useful for machining is reduced by the tool magazine mounted on the table. With respect to the changing of a tool in a machine in which feed axles are numerically controlled, there is also a drawback in that it is necessary to previously make a program of distances of movements of the respective axles necessary for the tool changing.
Another machine tool is known which is provided with a rotary tool magazine movable along an axis perpendicular to the axis of spindle. With this known machine tool the tool magazine is rotated and moved towards the spindle, so that one of tools stored in the tool magazine is coaxially aligned with the spindle, and subsequently, a relative movement between the magazine tool and the spindle along axis of the spindle is performed, so that the tool is set into the spindle. In accordance with such an arrangement, the mechanisms for rotation and movement of the tool magazine can be provided independently of the numerically controlled feed axles. However, in order to remove the tool from the spindle by moving the spindle axially away from the tool magazine with the tool being held by the tool magazine, it is necessary to release the tool from engagement with the spindle, prior to moving the spindle. That is, a mechanism securing the tool engaged with the spindle should be previously placed in a tool releasing position. For this purpose, a particular power actuator should be provided, thereby making the machine tool complicated in construction and expensive to manufacture.